All-channel tuner

ABSTRACT

An all-channel tuner using varactors in the tuner circuit comprises a selector shaft which is disposed axially movably and rotatably, and which has the first gear at the rear end; the second and third gears which selectively mesh with the first gear upon axial movements of said shaft; a planetary motion mechanism section which couples both the gears at predetermined reduction gear ratios by the planetary motion; and a variable resistor which is coupled to the planetary mechanism, and which adjusts an applied voltage to the varactors. The tuner circuit is tuned by the change in the applied voltage of the varactors.

[ 1 ALL-CHANNEL TUNER Primary Examiner-Milton Kaufman K 1 [75] Inventor Motoya ondo, Yokohama Japan Attorneyxemon, Palmer & Estabmok [73] Assignee: Tokyo Shlbaura Electric Co.,

Kawasaki-shi, Japan [5 7] ABSTRACT [22] Filed: July 30, 1971 An all-channel tuner using varactors in the tuner circuit comprises a selector shaft which is disposed axi- Appl' l67575 ally movably and rotatably, and which has the first gear at the rear end; the second and third gears which 52 us. c1. ..74/10.s2 selectively mesh with the first s p axial move- 51 1111. C1 ..Fl6h 35/18 of said Shah; a Planetary motion mechanism 581 Field of Search ..74/1052 Swim which P the Bears at predetermined reduction gear ratios by the planetary motion; and a variable resistor which is coupled to the planetary [56] References Cited mechanism, and which adjusts an applied voltage to UNITED TE PATENTS the varactors. The tuner circuit is tuned by the change in the applied voltage of the varactors. 2,052,701 9/1936 De Tar ..74/l0.52 X 2,118,859 5/1938 Newman ..74/10.52 7 Claims, 11 Drawing Figures PATENTEDJAIIZI 197a 7 3.701877 SHEET 2 OF 3 FIG. 6 +8 OUTPUT ANT T VHF .TUNER 33 i I R a 31 5*! #320 1 R; 25

UHF ANT TUNER RV LO UHF AMPLIFIER UHF OSCILLATOR VB 15 60 H v 360 36 INVENTOR.

ma r m flan 0o BY W fim VW firin /2415,

PATENTED JAN 2 SHEET 3 OF 3 FIG.8

FIG. 9

FIG.1O

FIGTH INVENTOR.

Ma OYA ONDO ALL-CHANNEL TUNER BACKGROUND OF THE INVENTION This invention relates to all-channel tuners, and more particularly to an all-channel tuner wherein an applied voltage of varactors is adjusted, thereby to receive all the channels of the VHF and UHF bands in the television broadcast.

In order to receive VHF and UHF television broadcasts with a single set of television receive, it has heretofore been carried out to rotate selector shafts, which are individually provided for the VHF and UHF channels, respectively, so as to select a desired station. Such tuner tends to be complicated in mechanism and large in size.

There has already been suggested an all-channel tuner system which uses varactors to conduct the station selection upon changes in a DC voltage. However, it is constructed such that DC voltages having been previously adjusted to tuned voltages are changed-over by usually four to eleven selection buttons,.so as to receive a desired station. Therefore, it has not been practical in that the whole system becomes large-sized and that it may not be utilized in a television set of a small-sized screen.

Further, there has been an all-channel tuner system which may be utilized also in a television set of a smallsized screen. With this system, however, a variable resistor for continuously varying the DC voltage is rotated by a knob, while the change-over selection between VHF and UHF is effected by another knob. Thus, the selection manipulation should be done by means of the two knobs. Moreover, in the manipulation, since the frequency varies largely in UHF and only slightly in VHF with respect to an identical rate of change of the DC voltage in the UHF and VHF bands, the manipulator feels it difficult to select a station to the disadvantage.

SUMMARY OF THE INVENTION An object of this invention is to provide an all-channel tuner which uses varactors in the tuner circuit, with which VHF and UHF television broadcasts may be selected by means of a single shaft, which is simple in construction and allows a manipulator to easily select stations in both the VHF and UHF bands, and which is made small in size.

According to an all-channel tuner of this invention, a selector shaft is carried on a frame in a manner to be rotatable and axially movable, and has the first gear fittedly secured at its rear end. Upon the axial movements of the selector shaft, the first gear is selectively caused to mesh with the second and third gears. The second and third gears are respectively fitted onto a driven member and a sun gear shaft, which are coupled to each other at a predetermined reduction gear ratio and in the planetary motion. The driven member is coupled to a shaft of a variable resistor, and with the rotation of the driven member, the resistance of the variable resistor is varied so as to'change an applied voltage to the varactors, thus conducting the station. In accordance with the tuner, the change-over between the VHF and UHF channels is effected by moving the selector shaft in the axial direction, while a desired station may be selected by rotating said shaft. Accordingly, VHF and UHF television broadcasts may be easily selected with the single selector shaft, and besides, a small-sized allchannel tuner may be attained owing to the employment of the varactors.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of a station-selecting voltage generator section of an all-channel tuner embodying this invention;

FIG. 2 is a sectional view of a planetary motion mechanism section in FIG. 1;

FIG. 3 is a sectional view taken along line III III in FIG. 2;

FIG. 4 is a front view of a cam mechanism in FIG. 1;

FIG. 5 is a front view of an indicator which is mounted on the tuner in FIG. 1;

FIG. 6 is a connection diagram of a tuner circuit section which is operated in combination with the tuner in FIG. 1;

FIG. 7 is a front sectional view showing a modification of the planetary motion mechanism section;

FIG. 8 is a side sectional view showing another embodiment of the planetary motion mechanism section;

FIG. 9 is a front view showing a modification of the cam mechanism;

FIG. 10 is a side view of an indicator in which VHF and UHF channel indicator parts are individually provided, respectively; and

FIG. 1 l is a front view of the indicator in FIG. 10.

DETAILED DESCRIPTION OF THE INVENTION Referring to FIG. 1, a selector shaft 12 is supported axially movably and rotatably on a frame 11 being U- shaped in section. The first gear 13 is secured to the rear end of the selector shaft 12, the second gear 14 and the third one 15 which, when the shaft 12 has moved in the axial direction, selectively mesh with the first gear 13 are provided at the back of the frame 11. The third gear 15 is fitted onto a driven member 17 which is rotatably supported on a cylinder 16 by a shaft, which cylinder is secured to a rear vertical plate 11a of the frame 11. The driven member 17 is coaxially provided with a long hole 18 as illustrated in FIG. 2. At that outer periphery of the driven member 17 which is located within the cylinder 16 a plurality of penetrating holes, three through holes 19 as shown in FIG. 3 in this embodiment, leading to the long hole 18 are perforated at equal intervals in the circumferential direction and perpendicularly to the axis of said driven member. Disposed in the penetrating holes 19 are planetary members having a predetermined diameter, e.g., balls 20. A sun gear shaft 22 on which the second gear 14 is mounted is rotatably inserted into the long hole 18. At that end of the sun gear shaft 22 which is located in the long hole 18, there is formed a taper portion 21, and the balls 20 are kept in contact with the outer periphery of the taper portion 21. The rear end of the sun gear shaft 22 is frontwardly urged by means of a pressure spring 23, so that the frictional contact between the taper portion 21 and the balls 20 and between the balls 20 and the inner wall of the cylinder 16 is established. Thus, when the sun gear shaft 22 is rotated, the balls 20 revolve along the inner wall of the cylinder 16 at a reduction gear ratio of:

where S diameter of that part of the sun gear shaft which is in contact with the balls,

d diameter of the ball.

Interlocking with the revolution of the balls 20, the driven member 17 rotates.

That shaft 17a of the driven member 17 which is located on the opposite side to the sun gear shaft 22 has one end of a flexible coupling 24 coupled thereto, the other end of which is connected to one end or the rear end of a shaft 26 of a variable resistor 25 being fixed to a front vertical plate 11b of the frame 11. The variable resistor 25 is so constructed as to turn in the endless manner, and the other end or the front end of the shaft 26 has the fourth gear 27 fittedly mounted thereon. The fourth gear 27 meshes at a reduction gear ratio of l 2 with the fifth gear 28 which is slidably rotatably fitted onto the selector shaft 12. In order to prevent the fifth gear 28 from moving along with the selector shaft 12 when said shaft is axially moved, the fifth gear is position-regulated by means of side plates 29 which are provided on both sides of the fourth gear 27 and which have a diameter larger than that of said fourth gear. On one end face of the fifth gear 28, a cam 30 is secured. As illustrated in FIG. 4, the cam 30 includes a semicircle portion 30a of a smaller radius and another semicircle portion 30b of a larger radius, and is substantially fan-shaped. A movable change-over piece 31 of a switch 33 is kept in contact with the outer peripheral edge of the cam 30, so that upon rotation of the-cam 30, the switch 33 is actuated. More specifically, during a half revolution of the cam 30 in the state in which the movable piece 31 is held in contact with the largerradius portion 30b, a contact 32a is closed, while a contact 32b is opened. In contrast, during a half revolution of the cam 30 in the state in which the movable piece 31 is kept in contact with the smaller-radius portion 30a, the contact 32a is opened, while the contact 32b is closed. The cam mechanism inclusive of the switch 33 is used for the change-over between the high channel and the low channel of the VHF band.

Onto the other end face of the fifth gear 28, an indicator 34 as shown in FIG. is secured on which the respective channel numbers of VHF and UHF stations are indicated. A change-over switch such as a slide switch 36 is fixed to the frame 11 in parallel with the selector shaft 12, and a manipulating rod 37 of the switch 36 is secured to the rear end of the selector shaft 12. The manipulating rod 37 moves following only the axial movement of the selector shaft 12, to actuate the slide switch 36. More specifically, the right end of the manipulating rod 37 as viewed in FIG. 1 is rotatably mounted on the extreme end part of the shaft 12. A switching circuit of the change-over switch 36 is connected to a tuner circuit so that, when the selector shaft 12 is being pushed, as shown FIG. 1 the UHF tuner circuit section may be rendered operative, whereas when the selector shaft 12 is pulled, from the state shown FIG. 1 the VHF tuner circuit section may be made operative.

There will now be described the operation in the case where the all-channel tuner constructed as described above is used with a tuner circuit connected therewith.

The all-channel tuner is employed in combination with a tuner circuit as shown, by way of example, in FIG. 6.

First, when a VHF station is to be selected, the selector shaft 12 is pulled. Then, the change-over switch 36 is changed-over to the VB side, i.e., a contact 36a and a diode 13 becomes cut off to render the VHF tuner circuit section operative. At this time, the first gear 13 meshes with the third gear 15. When, under this state, the selector shaftv 12 is rotated in a predetermined direction, then the first gear 13, the third gear 15, the driven member or outer member 17, and the flexible coupling 24 rotate in interlocking manner, respectively, and the shaft 26 of the variable resistor 25 coupled to the coupling 24 is rotated. The resistance R, of the variable resistor 25 is thereby varied, and a voltage ap plied through resistor R, to varactors D D D and D in the VHF tuner circuit is changed. The capacitances of the varactors D to D are changed in response to the voltage change, so that the VHF tuner circuit is tuned to the desired channel station. Since the fourth gear 27 and the fifth one 28 are caused to mesh at the gear ratio 1 2 with each other, one revolution of the shaft 26 will turn the cam 30 as well as the indicator 34 by a half revolution. The switch 33 operated by the cam 30 is changed-over to the low channel side, i.e., the contact 32a, during the half revolution, and switching diodes D to D are cutoff. When the switching diodes D to D become cut off, inductances L L L and L, respectively associated with the diodes are connected into the circuit to increase the tuning inductance, whereby the tuner circuit is set at the low channel reception owing to the relation f a( l/ v L). Accordingly, upon one further revolution of the shaft 26 of the variable resistor 25, the low channel, e.g., channels 2 to 6 in U; S. maybe tuned. When the shaft 26 of the variable resistor is rotated by one still further revolution, the switch 33 is changed-over to the high channel side, i.e., the contact 32b again, and then, the high channel such as channels 7 to 13 in U. S. may be tuned. The channel indication of the VHF channel is done by the indicator 34 secured to the fifth gear 28.

Next, the station selection of the UHF channel will be stated. When the selector shaft 12 is pushed, the

U-.V change-over switch 36 is changed-over to the UB side, i.e., a contact 3612, by means of the manipulating rod 37 interlocking with the shaft 12. Then, the diode 13 becomes on and a UHF signal is supplied to a UHF mixer circuit to be amplified, and simultaneously,

the first gear 13 meshes with the second gear 14. When the selector shaft 12 is rotated in the predetermined direction in this condition, the sun gear. shaft 22 is rotated at the prescribed reduction ratio between the first gear 13 and the second gear 14. The rotation of the sun gear-shaft 22 is transmitted to the driven member or planetary motion member 17 under the planetary motion action at the reduction gear ratio given in the foregoing expression (1). Upon rotation of the driven member 17, the shaft 26 of the variable resistor is rotated through the flexible coupling, a voltage applied to varactors D, to D -of the UHF tuner circuit is adjusted, and a desired UHF channel is tuned.

In case where a channel is to be selected with several channels passed over in the reception of the UHF broadcast, it takes a considerable time to select the desired channel since the portions from the selector shaft 12 to the shaft 26 of the variable resistor 25 and to the indicator 34 are subject to considerable deceleration. Accordingly, in such case, the selector shaft 12 is once pulled, the desired channel is brought nearer in the manipulative condition for receiving the VHF broadcast, the selector shaft 12 is pushed again to be changed-over to the UHF broadcast reception, and thus the selection is made. Then, the station selecting manipulationmay be carried out more quickly.

The planetary motion mechanism applied to the allchannel tuner of this invention may also be a construction wherein, as shown in FIG. 7, a plurality of planetary gears 43 are provided between a sun gear 41 and a ring gear 42 so as to mesh with both the gears 41 and 42, and the planetary gears 43 are journaled in a rotary plate 44. According .to such planetary motion mechanism, if the ring gear 42 is fixed and the sun gear 41 is rotated, the rotary member 44 rotates at a decelerated speed in the rotational direction of the sun gear 41. Furthermore, the planetary motion mechanism may be constructed such that, as shown in FIG. 8, a concave groove is provided in the outer periphery of the front end part of the sun gear shaft 22, and that the balls 20 are arranged between the concave groove and the inner wall of the cylinder 16 and with friction.

It is also possible to omit the change-over switch 36 in the embodiment in FIG. 1 and to construct a cam mechanism as illustrated in FIG. 9, so as to effect the change-over between VHF and UHF by means of the cam mechanism More specifically, a cam 45 is composed in a manner to have three radius sections 45a, 45b, and 450, while a change-over switch 47 is disposed in such a manner that a movable piece 46 of the change-over switch is brought into contact with the cam 45. The reduction gear ratio between the fourth gear 27 and the fifth gear 28 is set at 3 1. With such construction, in case where the selector shaft 12 is rotated in the prescribed direction and the movable piece 46 is kept in contact with the radius section 45a, the change-over switch 47 is operated so that the low channel of the VHF tuner is tuned. In other words, in FIGS. 6 and 9, the contacts 36a and 32a are closed. Next, when the movable piece 46 is positioned at the radius section 45 b, then the contact 36a holds the closure, the contact 32a is opened, and the contact 32b is closed, whereby the high channel of the VHF tuner is tuned. Further, when the selector shaft 12 is rotated and the movable piece 46 is located at the radius section 450, then the changeover switch 47 is so actuated as to open the contact 36a and to close the contact 36b. Thus, the UHF tuner circuit may be tuned to a desired channel station.

In addition, the indicator applied to the foregoing embodiment may also be constructed as shown in FIG. 10. More specifically, two gears 50 and 51 for UHF and for VHF are respectively provided at the front end part of the shaft 26 of the variable resistor 25. Fittedly mounted onto the selector shaft 12 in rotatable and slidable manner is a hollow shaft 53 on which a driven gear 52 meshing with the gear 51 for VHF at a gear ratio of l 2 is fittedly secured. At the front end of the hollow shaft 53, an indicator 54 for VHF channels is mounted. Onto the hollow shaft 53, there is rotatably and fittedly mounted a hollow shaft 56 to which a follower gear 55 for UHF as meshes with the gear 50 for UHF at a gear ratio of l i is rigidly secured. At the front end of the hollow shaft 56, an indicator 57 for UHF is attached. When the indicators are provided as stated above, the respective indications of the VHF and UHF channels may be individually done. When, in the station selection of the VHF television broadcast, the shaft 26 of the variable resistor 25 is rotated by two revolutions, the VHF indicator 54 is turned by one revolution to indicate channel 2 to channel 13. When, in the channel selection of the UHF television broadcast, the shaft 26 is rotated by one revolution, the UHF indicator 57 turns by one revolution to indicate channel 14 to channel 83 of the UHF channel. The fronts of the indicators 54 and 57 are seen in FIG. 1 1.

According to the all-channel tuner of this invention as described above, the station selection of a television broadcast in the VHF and UHF bands may be made very efficiently and reliably with a single selector shaft, and it may be manufactured in a small size.

What is claimed is:

1. An all-channel tuner comprising a selector shaft which is carried on a frame in a manner to be rotatable and axially movable; a first gear which is fittedly mounted on the rear end of said selector shaft; a second gear and a third gear which selectively mesh with said first gear upon axial movements of said selector shaft; a planetary motion mechanism section which planetarily couples said second and third gears at predetermined reduction gear ratios, said third gear being secured to a rotary shaft; a variable resistor which is secured to said frame, and which has a shaft being coupled to said rotary shaft of said planetary motion mechanism section; a cam which is slidably fitted onto said selector shaft, and which is operatively connected to rotate with said shaft of said variable resistor; and a switch mechanism section which is actuated by the rotation of said cam and the movement of said selector shaft.

2. An all-channel tuner according to claim 1, wherein said planetary motion mechanism section comprises a cylinder which is fixed to said frame; said rotary shaft being a driven member which is rotatably supported in said cylinder, which has a long hole coaxial therewith, and onto which said third gear is fitted; a sun gear shaft which is rotatably inserted intosaid long hole of said driven member, and onto which said second gear is fitted; a plurality of penetrating holes which are provided at the outer peripheral part of said driven member located within said cylinder, and which penetrate to said long hole; and a plurality of spherical bodies which are respectively provided in said penetrating holes, and which are kept in frictional contact with the inner wall of said cylinder and with the outer periphery of said sun gear shaft by spring means.

3. An all-channel tuner according to claim 2, wherein said sun gear shaft has a taper portion which is located within said long hole, and which is kept in frictional contact with said spherical bodies.

4. An all-channel tuner according to claim 2, wherein said sun gear shaft has an end which is located within said long hole, and which has at its outer periphery a semicircular concave groove kept in frictional contact with said spherical bodies.

5. An all-channel tuner according to claim 1, wherein said cam has a semi-circumference portion of a smaller radius and a semi-circumference portion of a larger radius and rotates along with said shaft of said variable resistor at a reduction gear ratio of 2 l, and wherein said switch mechanism section comprises a first change-over switch which is actuated by said respective radius portions of said cam and which is used for the change-over between a high channel and a low channel of the VHF band, and a second changeover switch which has a manipulating rod coupled to said selector shaft and interlocking with the axial movement of said selector shaft and which is used for the change-over between the VHF and UHF bands.

6. An all-channel tuner according to claim 1, wherein said cam has first, second and third radius portions respectively having different radii and rotates in a manner to interlock with said shaft of said variable resistor at a reduction gear ratio of 3 l, and wherein said switch mechanism section has contacts respectively actuated by said first, second and third radius portions of said cam and is used for the change-overvbetween the VHF and UHF bands and the change-over between a high channel and a low channel of the VHF band.

7. An all-channel tuner comprising a selector shaft which is carried on a frame in a manner to be rotatable and axially movable; a first gear which is fitted onto the rear end of said selector shaft; a second gear and a third gear which respectively mesh with said first gear at predetermined reduction gear ratios upon axial movements of said selector shaft; a planetary motion mechanism section which planetarily couples said second and third gears at predetermined reduction gear ratios, to a rotatable driven member; a variable resistor which is mounted on said frame, and which has a shaft coupled to said driven member of said planetary motion mechanism sectionzand rotating in a manner to inter-lock with said driven member; fourth and fifth gears which are fitted onto said shaft of said variable resistor; a first hollow shaft which is rotatably fitted onto said selector shaft; a sixth gear which is fixedly secured to said hollow shaft, and which meshes with said fourth gear at a reduction gear ratio of 1 2; a second hollow shaft which is rotatably fitted onto said first hollow shaft; a seventh gear which is fixedly secured to said second hollow shaft, and which meshes with said fifth gear at a reduction gear ratio of l l; a cam which is rotatably provided on said selector shaft, and which is connected with said sixth gear; a first change-over switch which is actuated in response to the rotation of said cam, and which is used in order to effect the change-over between a high channel and a low channel of the VHF band; a second change-over switch which is actuated in conformity with the axial movement of said selector shaft, and which is used in order to efi'ect the change-over between the VHF band and the UHF band; an indicatorvfor VHF-whichis attached to said.

first hollow shaft, and which indicates channel numbers for the VHF band; and an indicator for UHF which is attached to said second hollow shaft, and which indicates channel numbers for the UHF band.

i i 4! k 

1. An all-channel tuner comprising a selector shaft which is carried on a frame in a manner to be rotatable and axially movable; a first gear which is fittedly mounted on the rear end of said selector shaft; a second gear and a third gear which selectively mesh with said first gear upon axial movements of said selector shaft; a planetary motion mechanism section which planetarily couples said second and third gears at predetermined reduction gear ratios, said third gear being secured to a rotary shaft; a variable resistor which is secured to said frame, and which has a shaft being coupled to said rotary shaft of said planetary motion mechanism section; a cam which is slidably fitted onto said selector shaft, and which is operatively connected tO rotate with said shaft of said variable resistor; and a switch mechanism section which is actuated by the rotation of said cam and the movement of said selector shaft.
 2. An all-channel tuner according to claim 1, wherein said planetary motion mechanism section comprises a cylinder which is fixed to said frame; said rotary shaft being a driven member which is rotatably supported in said cylinder, which has a long hole coaxial therewith, and onto which said third gear is fitted; a sun gear shaft which is rotatably inserted into said long hole of said driven member, and onto which said second gear is fitted; a plurality of penetrating holes which are provided at the outer peripheral part of said driven member located within said cylinder, and which penetrate to said long hole; and a plurality of spherical bodies which are respectively provided in said penetrating holes, and which are kept in frictional contact with the inner wall of said cylinder and with the outer periphery of said sun gear shaft by spring means.
 3. An all-channel tuner according to claim 2, wherein said sun gear shaft has a taper portion which is located within said long hole, and which is kept in frictional contact with said spherical bodies.
 4. An all-channel tuner according to claim 2, wherein said sun gear shaft has an end which is located within said long hole, and which has at its outer periphery a semicircular concave groove kept in frictional contact with said spherical bodies.
 5. An all-channel tuner according to claim 1, wherein said cam has a semi-circumference portion of a smaller radius and a semi-circumference portion of a larger radius and rotates along with said shaft of said variable resistor at a reduction gear ratio of 2 : 1, and wherein said switch mechanism section comprises a first change-over switch which is actuated by said respective radius portions of said cam and which is used for the change-over between a high channel and a low channel of the VHF band, and a second change-over switch which has a manipulating rod coupled to said selector shaft and interlocking with the axial movement of said selector shaft and which is used for the change-over between the VHF and UHF bands.
 6. An all-channel tuner according to claim 1, wherein said cam has first, second and third radius portions respectively having different radii and rotates in a manner to interlock with said shaft of said variable resistor at a reduction gear ratio of 3 : 1, and wherein said switch mechanism section has contacts respectively actuated by said first, second and third radius portions of said cam and is used for the change-over between the VHF and UHF bands and the change-over between a high channel and a low channel of the VHF band.
 7. An all-channel tuner comprising a selector shaft which is carried on a frame in a manner to be rotatable and axially movable; a first gear which is fitted onto the rear end of said selector shaft; a second gear and a third gear which respectively mesh with said first gear at predetermined reduction gear ratios upon axial movements of said selector shaft; a planetary motion mechanism section which planetarily couples said second and third gears at predetermined reduction gear ratios, to a rotatable driven member; a variable resistor which is mounted on said frame, and which has a shaft coupled to said driven member of said planetary motion mechanism section and rotating in a manner to inter-lock with said driven member; fourth and fifth gears which are fitted onto said shaft of said variable resistor; a first hollow shaft which is rotatably fitted onto said selector shaft; a sixth gear which is fixedly secured to said hollow shaft, and which meshes with said fourth gear at a reduction gear ratio of 1 : 2; a second hollow shaft which is rotatably fitted onto said first hollow shaft; a seventh gear which is fixedly secured to said second hollow shaft, and which meshes with said fifth gear at a reduction gear ratio of 1 : 1; a cam which is Rotatably provided on said selector shaft, and which is connected with said sixth gear; a first change-over switch which is actuated in response to the rotation of said cam, and which is used in order to effect the change-over between a high channel and a low channel of the VHF band; a second change-over switch which is actuated in conformity with the axial movement of said selector shaft, and which is used in order to effect the change-over between the VHF band and the UHF band; an indicator for VHF which is attached to said first hollow shaft, and which indicates channel numbers for the VHF band; and an indicator for UHF which is attached to said second hollow shaft, and which indicates channel numbers for the UHF band. 